The present disclosure relates generally to the field of electrical drives. More particularly, the present disclosure relates to a modular embodiment of a pre-charge circuit for pre-charging a direct current (DC) bus in a power electronic device, such as an electrical drive.
In the field of power electronic devices, a wide range of circuitry is known and currently available for converting, producing, and applying power to loads. Depending upon the application, motor drive systems may include circuitry that converts incoming power from one form to another as used by the load. In a typical drive system, for example, a rectifier converts alternating current (AC) power (such as from a utility grid or generator) to direct current (DC) power. Inverter circuitry can then convert the DC power into a controllable AC power having a particular frequency for driving a motor at a particular speed. The inverter circuitry typically includes several high power switches, such as insulated-gate bipolar transistors (IGBTs), that are controlled by drive circuitry. Motor drive systems also often include power-conditioning circuitry, including capacitors and/or inductors, which may remove undesirable ripple currents from a DC bus coupled to a motor drive system.
During operation of a motor drive system, and particularly during start-up, high levels of in-rush current may be received by a motor drive in the motor drive system. The high levels of in-rush current may cause various adverse effects to the motor drive. To avoid these high levels of in-rush current during start-up, a typical motor drive system may include pre-charge circuitry that applies an initial current to the DC bus of the motor drive system prior to actually coupling a power source to the motor via the DC bus. As such, the pre-charge circuitry may charge a number of capacitors coupled to the DC bus before applying a full source voltage from the power source to the inverter via the DC bus. Such techniques may be referred to as pre-charging the DC bus.
Typical pre-charge circuitry may include components of a pre-charge circuit mounted on a flat array. Mounting the components on a flat array, however, may not be an efficient use of space. Moreover, mounting the components in this manner may also make replacing components of the pre-charge device challenging. As such, improved systems and methods for manufacturing pre-charge circuitry are desirable.